1. Technical Field
The present invention relates to pre-crash sensing systems for automotive vehicles, and more particularly, to pre-crash sensing systems having countermeasures operated in response to pre-crash detection.
2. Background
Auto manufacturers are investigating radar, lidar, and vision-based pre-crash sensing systems to improve occupant safety. Current vehicles typically employ accelerometers that measure decelerations acting on the vehicle body in the event of a crash. In response to accelerometers, airbags or other safety devices are employed.
In certain crash situations it would be desirable to provide information before forces actually act upon the vehicle when a collision is unavoidable.
Remote sensing systems using radar, lidar or vision based technologies for adaptive cruise control, collision avoidance and collision warning applications are known. These systems have characteristic requirements for false alarms. Generally, the remote sensing system reliability requirements for pre-crash sensing for automotive safety related systems are more stringent than those for comfort and convenience features, such as, adaptive cruise control. The reliability requirements even for safety related features vary significantly, depending upon the safety countermeasure under consideration. For example, tolerance towards undesirable activations may be higher for activating motorized belt pre-tensioners than for functions such as vehicle suspension height adjustments. Non-reversible safety countermeasures, including airbags, require extremely reliable sensing systems for pre-crash activation. However, the size of objects is typically not taken into consideration in the activation of such countermeasure devices.
It would therefore be desirable to provide a pre-crash sensing system that provides accurate determinations as to the presence of a potential collision target. It would also be desirable to provide a system that takes into consideration the size of the object detected.